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What’s 220 pounds to General Motors’ new 6.6-liter Duramax diesel V-8 engine? Not much, based on the minuscule differences between the performances of the 2017 GMC Sierra 2500HD tested here and a slightly smaller, extended-cab Chevrolet Silverado 2500HD with the same engine we tested earlier this year. This 8000-pound GMC—a high-zoot, crew-cab Denali model—is 9.5 inches longer and 220 pounds heavier than that Silverado, yet it trails the Chevy to 60 mph by only 0.3 second and by 0.2 second through the quarter-mile. This “slower” four-ton truck’s performance figures are remarkable: 6.5 seconds to 60 mph, and a quarter-mile time of 15 flat at 91 mph.

Rather than list the lighter-weight, more performance-oriented passenger cars that can match that feat, we’ll just say that piloting so much vehicle so quickly is a unique thrill. Imagine going neck and neck with a Fiat 124 Spider off the line while driving your house. It’s a bit like that. All credit goes to the updated Duramax diesel engine, which added $8800 to the bottom line of our Sierra 2500HD test truck. Shared with the Silverado, the V-8 puts out 445 horsepower and 910 lb-ft of torque. It’s the headline upgrade to the 2017-model Sierra 2500 and 3500 trucks, which otherwise change only with the additions of a ram-air hood scoop for Duramax-equipped models and a newly available dealer-installed lane-change camera system.

About that Engine . . .

The Sierra’s 6.6-liter Duramax diesel shares only its iron block and valvetrain layout with its predecessor. Everything else is new, including the turbocharger, aluminum cylinder heads, control unit, crankshaft, pistons, and exhaust. The result is a 48-hp jump over last year’s Duramax, while torque swells by a whopping 145 lb-ft. Although GM says the new engine is quieter than before, thanks to refinements and an insulated oil pan, the clattery rat-tat-tat diesel soundtrack is still (faintly) audible inside the cabin—even if the 67 decibels we measured inside at 70 mph are luxury car-like.

Who needs quiet, though, when the Duramax is so damn impressive at punting the Sierra around? With a smooth buildup to its midrange wallop, the diesel V-8 moves the Sierra smartly off the line. A fun activity is seeing how quickly one can slam into the truck’s top-speed limiter, which is set at 98 mph (the Sierra reaches 90 mph in 14.6 seconds); however imprudent, the rig could do more, since it’s still accelerating rather swiftly when it reaches that top speed. Compared to Power Stroke–equipped Ford F-250 and F-350 models we recently tested, this 2500-spec Denali was 0.4 second and 0.7 second quicker to 60 mph. We haven’t tested a 2017 model-year Ram 2500 with the optional Cummins diesel engine, but a 3500 dualie was 2.1 seconds slower to 60 mph. The EPA doesn’t require fuel-economy estimates for trucks this large, so GMC doesn’t provide any. We saw 14 mpg over the course of our test, and 18 mpg on our 200-mile highway test loop.

We didn’t tow anything with the Sierra 2500 during our time with it, mostly because there wasn’t anything on hand that was heavy enough to really tax it. Since tow ratings are the measuring contest favored by heavy-duty pickup-truck buyers, we’ll note that for 2017, Ford’s diesel F-350 with a dualie rear axle still takes top towing honors with a 32,000-pound maximum for a fifth-wheel gooseneck. The F-250 (with a regular rear axle) we tested earlier this year could lug up to 15,000 pounds from its hitch or another 400 pounds using a fifth wheel. This analogous four-door, four-wheel-drive three-quarter-ton GMC is rated up to 14,800 pounds using a fifth wheel or up to 13,000 pounds using a conventional trailer hitch. GMC says it focused on refining its trucks’ towing capability for a better drive near the Sierra’s weight maximums rather than increasing the peak figures, but the real point may be that all of these trucks can now tow far more than they need to.

When 8000 Pounds Is Lightweight

Ford has been making hay over its new-for-2017 F-series Super Duty trucks’ aluminum bodies and beds, which are said to reduce weight. In reality, the bodies’ mass savings are partially offset by the truck’s beefed-up steel frames and uprated driveline components, and the weight savings merely bring the previously heavy Fords in line with GM’s all-steel trucks, which saw no major changes to their frames or bodies this year. This is to say that, as before, the GMC Sierra 2500 is on the lightweight end of its class, and it drives that way.

The 2017 Ford’s maneuverability is a different story, having been greatly enhanced by its new variable-ratio steering system. The GMC, however, has always felt wieldy even on cramped city streets. This isn’t to imply the Sierra wouldn’t benefit from more precise steering; the hydraulically assisted setup suffers from loose on-center feel that allows some front-end wandering at highway speeds. There is no such play in the brake pedal, which operates with a pleasant firmness and without the odd, over-boosted, stepped sensation that plagues the F-series. The binders stop the massive GMC from 70 mph in 210 feet, a few feet longer than we recorded in the F-250. As is the case with most heavy-duty trucks, the GMC’s ride motions are abrupt over pockmarked pavement when unladen, although it is surprisingly tolerable.

GMC’s Denali trim level, available on every model it sells, is intended to be the ultimate expression of the brand’s aspirational luxurious-workhorse vibe. That certainly holds true here, at least in terms of the bells and whistles on board. Standard equipment includes leather seat surfaces, heated and ventilated front seats, a power-sliding rear window, dual-zone automatic climate control, power-adjustable pedals, a heated steering wheel, front and rear parking sensors, a backup camera, a Bose audio system, and an 8.0-inch touchscreen with Apple CarPlay and Android Auto integration. This comes at a luxury price, of course, with the four-wheel drive, crew-cab 2500 Denali starting at $60,090. Our truck stickered for $70,545 with the Duramax engine, a $995 sunroof, the $370 fifth-wheel-prep package, $180 for an upgraded off-road suspension, $55 roof marker lights, and a $55 radiator cover tallied in.

Less luxurious are the environs in which all of these toys are installed. The GMC is getting old, and the plain-Jane, rectilinear interior betrays its age in spite of the fancy veneer added by the Denali trim. Other rigs’ top-flight models do more convincing luxury-car impressions, particularly Ford’s Platinum spec. The F-series also has the Sierra beat with modern active-safety tech such as adaptive cruise control and lane-keeping assist. The GMC has only lane-departure warning, forward-collision warning, and the previously mentioned new dealer-installed trailer camera system that beams a feed from the attendant side mirror to the central display when the turn signal is activated. This feature wasn’t included on our test truck, but we’ve tried it on the Silverado and found it useful, if redundant—properly adjusted blind-spot mirrors show basically the same view and don’t require the driver to study the dashboard display while in motion.

The argument could be made that the old-school steel Sierra 2500 doesn’t need newfangled tech to bolster its appeal. Pricey Denali trim aside, the GMC is a straightforward tool, one with an incredible diesel engine option.